<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .content {
            width: 500px;
            height: 500px;
            background-color: gainsboro;
            margin: 40px auto;
            display: flex;
            justify-content: center;
            align-items: center;
        }

        /* 大圆的样式 */
        .content .bigCircle {
            width: 330px;
            height: 330px;
            border: 20px solid;
            border-radius: 50%;
            display: flex;
            justify-content: center;
            align-items: center;
            /* 加载动画 */
            animation: breath 3s linear infinite alternate;
        }

        /* 小圆的样式 */
        .bigCircle .smallCircle {
            width: 280px;
            height: 280px;
            border: 10px solid;
            border-radius: 50%;
            /* 加载动画 */
            animation: breath 3s linear infinite alternate;
        }

        @keyframes breath {
            0% {
                transform: scale(0.6);
                border-color: orange;
            }

            25% {
                transform: scale(0.7);
                border-color: red;
            }

            50% {
                transform: scale(0.8);
                border-color: purple;
            }

            75% {
                transform: scale(0.9);
                border-color: blue;
            }

            100% {
                transform: scale(1);
                border-color: orange;
            }
        }
    </style>
</head>

<body>
    <div class="content">
        <div class="bigCircle">
            <div class="smallCircle"></div>
        </div>
    </div>
</body>

</html>